Finding the Fourth Proportional to 91.89, 137.07 and 90.72

Step by Step Solution

1. Step 1: Write the proportion equation
   91.89 : 137.07 = 90.72 : x
2. Step 2: Convert to fraction form
   91.89/137.07 = 90.72/x
3. Step 3: Cross multiply
   91.89x = 137.07 × 90.72
4. Step 4: Simplify right side
   91.89x = 12,434.99
5. Step 5: Solve for x
   x = 12,434.99/91.89
6. Step 6: Final answer
   x = 135.32